In the production of a usable gas by the combustion of a carbonaceous fuel, the process is operated most effectively under a high temperature and high pressure conditions. For example, for the production of a gas from a particulated coal or coke, a preferred operating temperature range of about 2400.degree. to 2600.degree. F. is maintained, at a pressure of between about 5 to 250 atmospheres.
The harsh operating conditions prevalent in such a method, and in particular the wide temperature variations experienced, imposes a severe strain on many segments of the gasifier or reactor unit. The present invention is addressed to an improvement in the structure of the gasifier, and particularly to the quench ring and the dip tube structure. The latter, by their functions in the apparatus, are exposed to the maximum temperature conditions by virtue of the hot product gas which comes in contact with these members directly from the combustion chamber.
U.S. Pat. No. 4,218,423, issued Aug. 18, 1980 to Robin et al., illustrates one form of quench ring and dip tube which can be improved through use of the present arrangement. The industry, however, has experienced a chronic defect in gasifier construction due to the physical stress imposed on the quench ring. This comes as a result of its proximity to the hot gas, as well as to the flow of liquid coolant which it conducts.
These difficulties, experienced as a result of high temperature conditions, generally manifest themselves in the form of minute cracks and fissures which develop in the quench ring. The latter tend to form in areas particularly where sharp corners are present such that any physical or thermal stress would be magnified and precipitate water leakage into the gasifier.
Further, the toroidal configuration of a quench ring often prompts the development of permanent strains and cracks due to the thermal expansion of the ring.
Toward overcoming this prevalent operating defect in gasifiers of the type contemplaced, there is presently disclosed a combination dip tube and quench ring which are so positioned and interrelated as to minimize thermal stresses normally encountered during a gasification period. Further, the water carrying quench ring is segmented into a plurality of members which are cooperatively arranged in a circular configuration with water cooled expansion joints between the respective segments.
It is therefore an object of the invention to provide an improved gasifier for producing a usable gas, in which the dip tube is wetted by a coolant holding quench ring.
A further object is to provide a liquid cooling system for a gasifier which minimizes thermal expansion stresses in the quench ring due to high temperature expansion realized due to contact with produced gas being conducted from the gasifier's combustion chamber.
A still further object is to provide a gasifier cooling system wherein a novel liquid holding, segmented quench ring is positioned to cool the dip tube while minimizing thermal stress to itself.